Deputy Attorney General Rod Rosenstein’s appointment of Robert S. Mueller III as “special counsel” for purposes of the so-called Russia investigation underscores a point I have made through the years, whenever the subject of special prosecutors or independent counsels rears its head. Because there is no such thing as an independent counsel (i.e., a lawyer who wields prosecutorial power independent of the executive branch), the structure of a “special counsel” arrangement will never give anyone confidence. A special counsel is appointed by the attorney general (here, it’s the deputy attorney general because AG Jeff Sessions has recused himself). A special counsel also reports ultimately to the president — meaning that, like any other executive-branch official (other than the vice president), a special counsel serves at the pleasure of the president and may be dismissed at any time.

Therefore, the public perception that the special-counsel arrangement has integrity hinges exclusively on the lawyer who is appointed. It is the lawyer’s reputation for probity and professionalism, and that alone, that can convince people a real investigation, governed by law and evidence not politics, is being conducted.

In this instance, Rosenstein has chosen well.

Bob Mueller is a widely respected former prosecutor, U.S. attorney, high-ranking Justice Department official, and FBI director. He is highly regarded by both parties. This is perhaps best exhibited by the fact that when his ten-year term as the FBI director appointed by President George W. Bush expired in 2011, President Obama asked him to stay on for an additional two years, and Congress quickly agreed to extend his term. He is a straight shooter, by the book, and studiously devoid of flash.

He is also fondly remembered by Democrats as having joined then–deputy attorney general James Comey in the famous showdown, at then–attorney general John Ashcroft’s hospital bed, over President Bush’s warrantless surveillance program. It was at the insistence of Comey and Mueller that Bush made modifications to the program to bring it into the Justice Department’s revised understanding of lawfulness.

Mueller notwithstanding, there remain peculiar aspects of this special-counsel appointment. Foremost of these (as we’ve also repeatedly noted) is that the so-called Russia investigation is a counterintelligence investigation, not a criminal investigation. In the Justice Department, counterintelligence investigations are not assigned a prosecutor as criminal cases are because the point is to collect information about a foreign power (an investigative and analytical intelligence function), not to build a prosecutable case against a suspect for a violation of penal law.

Lawyers in the Justice Department’s National Security Division (NSD) oversee the government’s domestic national-security operations and assist the FBI in obtaining warrants from the Foreign Intelligence Surveillance Court — court orders that authorize the agents to collect information and monitor suspected foreign agents. Presumably, Mueller will supplant the NSD for purposes of the Russia investigation, which is described in Rosenstein’s order as an investigation of “any links and/or coordination between the Russian government and individuals associated with the campaign of President Donald Trump.” That is to say, when it comes time to announce the conclusions of this counterintelligence probe, it will be Mueller making the findings.

In addition, the special counsel will have broad authority to investigate any additional matters that have already arisen or that may arise directly from the investigation. That entails two things. First, to the extent the counterintelligence investigation has incidentally uncovered any suspected criminal misconduct, the special counsel has jurisdiction to investigate and prosecute. This would presumably include the reported investigation of retired General Michael Flynn, the former national-security adviser — the investigation that is the subject of the controversial Comey memo, which is said to recount a conversation between President Trump and the former FBI director.

When it comes time to announce the conclusions of this counterintelligence probe, it will be Mueller making the findings.

Second, to the extent that crimes arise because of the investigation — e.g., if witnesses are caught lying to investigators or the grand jury — Mueller will have jurisdiction to investigate and charge such offenses.

These two components make it impossible to answer the pressing question of how long Mueller’s investigation will last. The FBI (and other intelligence agencies) have been investigating the Russia counterintelligence matter for nearly a year, and a great deal of work has already been done on it. I imagine there is a chance it could be wrapped up within a few months — Mueller is a quick study and a hard worker, it won’t take him long to get up to speed.

What can really slow these investigations down is the prosecution of ancillary criminal cases. If there are none, things can be wrapped up in short order. But if people are indicted, it could go on for years. Mueller is not a Lawrence Walsh type. He will not want to make a career out of this. At the same time, if serious criminal wrongdoing is uncovered, he won’t turn a blind eye.

Why is it called a “special counsel”? Originally, the concept was known as “special prosecutor,” Archibald Cox being the most famous. In 1978, the Democrat-controlled Congress enacted the Ethics in Government Act, which created the “independent counsel” — a constitutional anomaly that purported to transfer executive authority to the judicial branch (the D.C. Circuit Court of Appeals) for purposes of, among other things, appointing a lawyer to investigate government misconduct. The institution was skewered by Justice Antonin Scalia in his famous Morrison v. Olson (1988) dissent. Democrats lost their appetite for independent counsels when Bill Clinton was investigated by one. The office was thus allowed to sunset in 1999.

It was replaced by the current “special counsel” — which is not called “independent” because, as noted above, it isn’t. But formal independence is less important than the perception of integrity (flowing from the reality of integrity). Bob Mueller has that. I remain a skeptic of special prosecutors or special counsels. Democrats are so Trump-deranged that I suspect, despite Mueller’s solid reputation, they will claim the fix is in if impeachment does not appear to be on the horizon in short order. But most people will give Mueller a chance. And he deserves that.